Spatio-temporal Analysis of Annual Rainfall Breakpoints in the Republic of Guinea (West Africa)

Diakaria Diallo^{1, 2}, Moussa Mamady Traore^{1, 3,} , Tamba Nicolas Millimono^{2, 4}, Mamadou Bailo Barry⁵, Ibrahima Kalil Kanté^{2, 6}, Mamadou Keita⁷, Hambaliou Balde², Bakary Traore⁸, Abdoulaye Baniré Diallo⁹, Maoro Beavogui¹⁰ and Idrissa Diaby²

¹High Institute for Education Sciences of Guinea (ISSEG), Conakry, Republic of Guinea

²Laboratory for Teaching and Research in Applied Energy (LEREA), Gamal Abdel Nasser University of Conakry (UGANC), Conakry, Republic of Guinea

³Laboratory for Teaching and Research in Applied Energy (LEREA), Gamal Abdel Nasser University of Conakry (UGANC), Conakry, Republic of Guinea;Siméon Fongang Laboratory of Atmospheric and Ocean Physics (LPAO-SF), Cheikh Anta Diop University of Dakar (UCAD), Dakar, Senegal;City of Science and Innovation of Guinea (CSIG), Conakry, Republic of Guinea

⁴Institute for Science and Technology of Mamou (IST), Mamou, Republic of Guinea;Siméon Fongang Laboratory of Atmospheric and Ocean Physics (LPAO-SF), Cheikh Anta Diop University of Dakar (UCAD), Dakar, Senegal

⁵University of Labe (UL), Labe, Republic of Guinea

⁶Siméon Fongang Laboratory of Atmospheric and Ocean Physics (LPAO-SF), Cheikh Anta Diop University of Dakar (UCAD), Dakar, Senegal;National Directorate of Meteorology (DNM), Conakry, Republic of Guinea

⁷Institute for Environmental Research of Guinea (IREG), Conakry, Republic of Guinea

⁸Department of Mathematics, University of N'Zérékoré(UZ), N'Zérékoré, Republic of Guinea

⁹City of Science and Innovation of Guinea (CSIG), Conakry, Republic of Guinea

¹⁰National Directorate of Meteorology (DNM), Conakry, Republic of Guinea

Cite this paper:
Diakaria Diallo, Moussa Mamady Traore, Tamba Nicolas Millimono, Mamadou Bailo Barry, Ibrahima Kalil Kanté, Mamadou Keita, Hambaliou Balde, Bakary Traore, Abdoulaye Baniré Diallo, Maoro Beavogui and Idrissa Diaby. Spatio-temporal Analysis of Annual Rainfall Breakpoints in the Republic of Guinea (West Africa). Applied Ecology and Environmental Sciences. 2026; 14(2):44-52. doi: 10.12691/aees-14-2-2

Abstract

Rainfall variability in West Africa represents a major scientific issue due to its direct impacts on water resources, agriculture, and socio-economic systems. In Guinea, a country highly dependent on precipitation regimes, recent observations suggest a non-stationary evolution of the climate, characterized by alternating wet and dry phases as well as potential changes in rainfall patterns. In this context, the study aims to analyze the spatio-temporal variability of annual precipitation between 1986 and 2015 in order to identify and characterize the main climatic breakpoints across the Guinean territory. The study is based on high spatial resolution CHIRPS v2.0 satellite data (0.05°), aggregated into annual totals and then standardized using the Standardized Precipitation Index (SPI). The statistical analysis combines several complementary non-parametric change-point detection methods, including the Pettitt test, the Lee & Heghinian test, and Hubert segmentation, applied across the four natural regions of Guinea. This approach makes it possible to identify discontinuities in rainfall time series, assess their significance, and compare their spatial distribution according to regional climatic gradients. The results highlight strong interannual rainfall variability and the existence of a major climatic shift beginning in the mid-1990s, reflecting a reorganization of the rainfall regime. A second phase of change, observed between 1999 and 2015, reveals an asynchronous and spatially heterogeneous dynamic, with contrasting behaviors across the natural regions. Overall, an increase in interannual variability and an intensification of hydroclimatic extremes is observed. In conclusion, the Guinean climate appears to have undergone a profound restructuring, characterized by increasing instability of the precipitation system, underscoring the need to integrate these breakpoints into adaptation strategies and water resource management planning

Keywords:
Rainfall variability Climate change Spatio-temporal analysis Change-point detection Guinea

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References:

[1]	Nicholson, S. E., “The West African Sahel: A review of recent studies on the rainfall regime and its interannual variability,” Wiley Interdisciplinary Reviews: Climate Change, 4(1). 17–27. 2013.
[2]	Sultan, B. and Gaetani, M., “Agriculture in West Africa in the twenty-first century: Climate change and impacts uncertainties,” Frontiers in Plant Science, 7. 2072. 2016.
[3]	Lamb, P. J., “West African water vapor variability and its relation to rainfall,” Monthly Weather Review, 111(8). 1720–1734. 1983.
[4]	Nicholson, S. E., “Sub-Saharan rainfall: 1951–1983,” Journal of Climate and Applied Meteorology, 24(2). 1388–1409. 1985.
[5]	Paturel, J. E., Servat, E., Kouamé, B., Boyer, J. F., Lubès-Niel, H. and Masson, J. M., “Climatic variability in humid Africa along the Gulf of Guinea. Part II: An integrated regional approach,” Journal of Hydrology, 191(1–4). 56–91. 1997.
[6]	Hubert, P., Carbonnel, J. P. and Chaouche, A., “Segmentation des séries hydrométéorologiques. Application à des séries de précipitations et de débits de l’Afrique de l’Ouest,” Journal of Hydrology, 110(3–4). 349–367. 1989.
[7]	Pettitt, A. N., “A non-parametric approach to the change-point problem,” Applied Statistics, 28(2). 126–135. 1979.
[8]	Lubès-Niel, H., Masson, J. M., Paturel, J. E. and Servat, E., “Variabilité climatique et statistiques des ruptures dans les séries hydrologiques en Afrique de l’Ouest et centrale,” Hydrological Sciences Journal, 43(6). 937–950. 1998.
[9]	Lee, S. and Heghinian, S. M., “A shift-of-mean level detection method for non-stationary time series,” Water Resources Research, 13(6). 1401–1409. 1977.
[10]	Mahé, G. and Olivry, J. C., “Assessment of freshwater yields to the ocean along the West and Central African coasts,” Hydrological Sciences Journal, 44(6). 941–953. 1999.
[11]	Diallo, I., Giorgi, F. and Deme, A., “Rainfall variability and climate change in Guinea: Trends and extreme events,” Climate Research, 56(2). 123–137. 2013.
[12]	Kante, I. K., Badiane, D., Diaby, I. and Diouf, I., “Seasonal variability of rainfall and thunderstorm in Guinea over the period 1981 to 2010,” African Journal of Environmental Science and Technology, 13(9). 324–341. 2019.
[13]	Traore, M. M., Wane, D., Camara, I., Millimono, T. N., Kanté, I. K., Barry, M. B., ... and Sall, S. M., “Characterization of Precipitation Indices in the Republic of Guinea Using In-Situ Data,” 2025.
[14]	Gourou, P., La terre et l’homme en Afrique, Flammarion, Paris, 1962.
[15]	Béavogui, K., Camara, M. and Diallo, A., “Variabilité des précipitations et jours de pluie en Guinée forestière,” Revue des Sciences de l’Eau et du Climat en Afrique de l’Ouest, 5(2). 45–58. 2011.
[16]	Paturel, J. E., Servat, E., Kouamé, B., Boyer, J. F., Lubès-Niel, H. and Masson, J. M., “Climatic variability in humid Africa along the Gulf of Guinea. Part II: An integrated regional approach,” Journal of Hydrology, 191(1–4). 56–91. 1997.